Historically, this brings us from simple productivity-focused assistants with more generally device-based assistants. These assistants typically offer CIR integrated throughout their functionality and often are integrated with personal devices (e.g. mobile phones, situated speakers). In addition to the examples like Apple's Siri, this includes assistants such as Google Assistant, and Amazon Alexa. These voice-based conversational assistants must go beyond the chatbot interactions described above and tackle challenges of voice recognition in noisy environments and increasingly multi-modal and multi-party interactions. As an example Alexa [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]} highlights an interesting trend where a situated speaker interacts with multiple-parties (e.g., all of the members of a household) rather than a single party as is the case with a personal productivity-agent. This has both given rise to an increase in interest in speaker identification as well as other authentication mechanisms to be able to provide personal productivity functionality as well as information-seeking, chit-chat, recommendation, and task-completion. While a full discussion of device-based assistants is beyond the scope of this book, we see these devices not only continuing to become more conversational, but also see an increasing trend in research to customize the experience to different types of users (e.g. kids vs. adults) different situations (e.g. theme parks vs. offices) and different scenarios (e.g. entertainment vs. education).
